I was walking on the street __ suddenly lighting hit the building.A where B while C when D how

I was walking on the street __ suddenly lighting hit the building.A where B while C when D how
I was walking on the street __ suddenly lighting hit the building.
A where B while C when D how

I was walking on the street __ suddenly lighting hit the building.A where B while C when D how
正确答案B
when表示时间点.后面的suddenly也表示了是时间点,所以必须用when